1. Field of the Invention
This invention relates to a biomaterial in the field of tissue engineering for repairing nerve tissue and bone tissue. Specifically, the present invention relates to an RGD polypeptide grafted poly (glycolic acid-L-lysine-L-lactic acid)/β-tricalcium phosphate composite material, which is used to prepare nerve conduit or porous bone scaffold so as to repair the defects of nerve tissue or bone tissue. A method for preparing the composite material is also described.
2. Description of the Related Art
Tissue defects such as peripheral nerve defects are clinical common injuries. Natural bioactive materials, such as autologous nerve, skeletal muscle, blood vessel, membranous tubule, are mainly used in the traditional ways for repairing the peripheral nerve defects. However, these methods exhibit some shortcomings, for example, the second surgery, limited quantity of autologous bioactive materials. In addition, the collapse, due to short of blood, would cause hypoplasty and adhesion of tissue, which could further lead to scar tissue hyperplasia. Moreover, nerve allograft transplantation can also be used, but exhibits the problems of immune response and low success rate. In addition, the non-natural biomaterials such as demineralized bone tube, nylon fibre tube, silica gel pipe, polyurethane tube can also be utilized to repair the nerve tissue defect. Nevertheless, they can not be degraded and absorbed by human body and need to be taken out by the second surgery resulting in the damage of nerve tissue again.
In order to solve the problems described above, researchers are always making great efforts to look for the biodegradable materials which can repair the tissue defects. Now the biomaterials for preparing nerve conduit are mainly some biodegradable natural polymers and synthetic polymers. The natural polymers such as collagen and fibrin possess cell identification signal due to the specific amino acid sequence, which is advantageous to cell adhesion. They have good biocompatibility and cellular affinity. But the disadvantages are the poor degradation property and poor mechanical behavior. The degradation property and mechanical behavior of the synthetic polymers such as poly (glycolic acid) (PGA), poly (lactic acid) (PLA) and poly (lactic-co-glycolic acid) (PLGA) are better than the natural polymers. However, the biocompatibility and cellular affinity of synthetic polymers are worse than natural polymers. Moreover, the catabolite of synthetic polymers exhibits acidity, which will easily result in the aseptic necrosis of tissue.